The present invention relates to a decorative sheet for use, for example, in building interior materials, such as walls, and surface materials of, for example, fittings, such as doors, and furniture. More particularly, the present invention relates to a decorative sheet which possesses excellent anti-transferability to a cellophane pressure-sensitive adhesive tape and can be stably produced.
In general, surface properties, such as scratch resistance and stain resistance, have hitherto been required of decorative sheets used in the above applications. In order to cope with this, for example, Japanese Patent Publication No. 31033/1974 discloses a decorative sheet which has been produced by printing a pattern layer on a paper substrate, coating an unsaturated polyester prepolymer coating composition onto the surface of the printed substrate to form a coating, and then applying an electron beam to the coating to cause crosslinking and curing of the coating, thereby forming a surface protective layer.
Regarding the surface properties, in some cases, the anti-transferability to a cellophane pressure-sensitive adhesive tape is required such that, when paper (such as a poster or a calendar) or the like is applied to the decorated sheet with a cellophane pressure-sensitive adhesive tape and is then peeled off from the decorative sheet, only the cellophane pressure-sensitive adhesive tape is cleanly peeled off without the separation of the pattern layer, the substrate layer or other layer together with the tape. In order to meet this demand, for example, Japanese Patent No. 2856862 discloses a decorative sheet, as a sheet wherein not only surface properties, such as abrasion resistance, chemical resistance, and stain resistance, but also the anti-transferability to a cellophane pressure-sensitive adhesive tape has been taken into consideration, which has been produced by printing a pattern layer onto a paper substrate, coating an ionizing radiation-curable resin coating composition comprising an (meth)acrylate prepolymer and an (meth)acrylate monomer and, added thereto, silicone (meth)acrylate as a release agent on the printed substrate to form a coating, and applying an electron beam or ultraviolet light to the coating to cause crosslinking and curing of the coating, thereby forming a surface protective layer.
When attention is given to the anti-transferability to a cellophane pressure-sensitive adhesive tape, however, the method described in Japanese Patent No. 2856862 has the following drawbacks. Specifically, in the formation of the surface protective layer, wherein the type of and amount of the silicone (meth)acrylate added has been taken into consideration, since the silicone component is likely to localize (coagulate), the formed decorative sheet does not always have satisfactory anti-transferability to a cellophane pressure-sensitive adhesive tape. The addition of finely divided silica as a dispersant to prevent the localization can provide desired anti-transferability to a cellophane pressure-sensitive adhesive tape. This, however, poses a different problem. More specifically, the addition of the finely divided silica deteriorates the stability of the ionizing radiation-curable resin coating composition for the formation of the surface protective layer, and, during the storage of the coating composition, the dispersion state varies with the elapse of time. This leads to a variation in properties of the formed decorative sheet and thus makes it impossible to produce decorative sheets having stable properties including the anti-transferability to a cellophane pressure-sensitive adhesive tape.
Accordingly, it is an object of the present invention to provide a decorative sheet which possesses satisfactory anti-transferability to a cellophane pressure-sensitive adhesive tape and can be stably produced.
In order to attain the above object, according to the present invention, there is provided a decorative sheet comprising: a substrate; and, stacked on the surface of the substrate, at least a surface protective layer formed of a crosslinked cured product of an ionizing radiation-curable resin composition containing silicone (meth)acrylate as a release agent and a polyorganosiloxane organic copolymer as a dispersant.
The incorporation of the polyorganosiloxane organic copolymer, in addition to the silicone (meth)acrylate, into the ionizing radiation-curable resin composition for the surface protective layer can prevent the localization of the silicone (meth)acrylate, can provide satisfactory anti-transferability to a cellophane pressure-sensitive adhesive tape, can prevent a variation in this property, can prevent a change in the state of dispersion of the silicone (meth)acrylate in the coating composition with the elapse of time, and thus can realize stable production of decorative sheets. The silicone (meth)acryalte functions as a release agent, and the polyorganosiloxane organic copolymer functions as a dispersant for the release agent.